In earlier studies investigators claimed that subnormal cortisol response using plastic tubes might result from cosyntropin adherence to the tube and loss of the delivered dosage. It was shown that 21.6-58.6% of ACTH dosage had not been recovered when pushed through 20.3 cm plastic tube, and loss of ACTH may be up to 70% when cosyntropin was delivered through a plastic 30 cm scalp vein set.